Named after the German chemist Robert Wilhelm Bunsen, who contributed to its development, the Bunsen burner was already known to Michael Faraday, who may have created the first design. The idea behind the Bunsen burner is to reduce the considerable loss in heat energy typical in ordinary gas burners. This reduction of energy waste is accomplished by using a mixture of gas and air, the optimal proportion being three volumes of air to one of gas, instead of pure gas. As a result, combustion is intensified, producing a nonluminous but remarkably hot flame.
The Bunsen burner consists essentially of a long metal tube set on a flat base. Gas enters the burner through a hole in the bottom of the tube. Some burners have a gas adjustment screw that allows one to control the amount of gas entering the tube. With burners lacking a gas adjustment screw, gas flow can be controlled only at the supply valve. A second opening at the bottom of the metal tube allows air to enter and mix with the gas. The air inlet may be the bottom opening of the tube itself, or it may be a pair of holes cut into the tube near the base. The amount of air entering the tube in the former design was controlled by a flat piece of metal that can be slid across the hole to allow more or less air to enter. Some burners have threaded bases that allow the air supply to be controlled by turning the tube. In the second design described above, air supply is controlled by a collar that covers the hole in the tube. The collar can be rotated to allow more or less air to enter the tube.
The gas-air mixture is ignited at the top of the barrel. The flame produced at this point commonly consists of two cones. The outer cone is blue, while the inner remains quite pale, almost invisible. The hottest part of the burner flame is at the tip of the inner cone, where a rich supply of air ensures the nearly total combustion of the gas. The temperature at this point may be in excess of 3,272°F (1,800°C) in an inexpensive laboratory burner.
Beyond the laboratory, the the principle of Bunsen combustion is widely used in industry, in gas furnaces, and in everyday life, as exemplified by the kitchen gas range.
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